IBM Creates MRI With 100M Times the Resolution

An anonymous reader writes "IBM Research scientists, in collaboration with the Center for Probing the Nanoscale at Stanford University, have demonstrated magnetic resonance imaging with volume resolution 100 million times finer than conventional MRI. This result, published today in the Proceedings of the National Academy of Sciences, signals a significant step forward in tools for molecular biology and nanotechnology by offering the ability to study complex 3D structures at the nanoscale."

Comments

High resolution but small volume

[kebes]

The actual scientific paper is:
C. L. Degen, M. Poggio, H. J. Mamin, C. T. Rettner, D. Rugar Nanoscale magnetic resonance imaging PNAS 2009, doi: 10.1073/pnas.0812068106.

The abstract:

We have combined ultrasensitive magnetic resonance force microscopy (MRFM) with 3D image reconstruction to achieve magnetic resonance imaging (MRI) with resolution <10 nm. The image reconstruction converts measured magnetic force data into a 3D map of nuclear spin density, taking advantage of the unique characteristics of the 'resonant slice' that is projected outward from a nanoscale magnetic tip. The basic principles are demonstrated by imaging the 1H spin density within individual tobacco mosaic virus particles sitting on a nanometer-thick layer of adsorbed hydrocarbons. This result, which represents a 100 million-fold improvement in volume resolution over conventional MRI, demonstrates the potential of MRFM as a tool for 3D, elementally selective imaging on the nanometer scale.

I think it's important to emphasize that this is a nanoscale magnetic imaging technique. The summary implies that they created a conventional MRI that has nanoscale resolution, as if they can now image a person's brain and pick out individual cells and molecules. That is not the case! And that is likely to never be possible (given the frequencies of radiation that MRI uses and the diffraction limit that applies to far-field imaging.

That having been said, this is still a very cool and noteworthy piece of science. Scientists use a variety of nanoscale imaging tools (atomic force microscopes, electron microscopes, etc.), but having the ability to do nanoscale magnetic imaging is amazing. In the article they do a 3D reconstruction of a tobacco mosaic virus. One of the great things about MRI is that is has some amount of chemical selectivity: there are different magnetic imaging modes that can differentiate based on makeup. This nanoscale analog can use similar tricks: instead of just getting images of surface topography or electron density, it could actually determine the chemical makeup within nanostructures. I expect this will become a very powerful technique for nano-imaging over the next decade.

Re:Interesting!

[ViennaSt]

Unfortunately, this 3D MRI can not be applied to imaging the human brain yet.

One problem is that though this machine has great spatial resolution (precision in space)....it may not have great temporal resolution (precision in time).

In regards to your curiosity about imaging dendritic connections: It may image where/how the connections are made, which is a great leap for Neuroanatomists. But it cannot measure or record the hundreds of thousands of mechanisms and live actions that the dendrites/axons/cell bodies and their connections make during every one action potential that takes place...Even if this machine could measure outside the nanoscale.

Here's why: Neurons may fire a number of action potentials in millisecond time and increase/decrease in volume as the influx of sodium brings in water into the cell causing it to expand. As enough sodium (positively charged particals) are in the cell causing a depolarization, the voltage-gated ion channels shut off and K+ outflux/Na+ influx ceases. The cell hyperpolarizes, shrinks in volume and it's morphology is changed drastically once again. To capture all this change with such fine resolution is a feat, that sadly, cannot be accoplished by this 3D Machine--since everything it measures must be fixed and perfectly still. What neuroscientist use now for "partial real time brain imaging" is a function MRI or fMRI which measure changes in metabolism (glucose metabolism to be exact) but compromises the great spatial resolution this 3D machine has for the temporal resolution.